House Speaker Paul Ryan took the extraordinary step of saying he isn’t ready to support Donald Trump, and Trump fired right back, igniting a spat that pits one of the nation’s most popular and prominent Republicans against his party’s presumptive nominee.

Putting the brakes on Trump’s coronation, Ryan said on CNN that Trump needed to stop the bullying and demonstrate his conservative credentials in order to win the speaker’s support.

“I hope to support our nominee,” Ryan said. “At this point, I’m just not there right now.”

“Perhaps in the future we can work together and come to an agreement about what is best for the American people,” Trump said in a statement.

Ryan’s remarks were the latest sign of just how much work Trump will have to do just to bring Republicans along with him -- let alone the rest of the country -- after an unusually divisive and bruising presidential primary. And Trump signaled he may not be interested in working to win over party elites.

Trump-Ryan Meeting

“Both committed to sitting down and actually talking this out,” Priebus said. “I think it’s going to work out but in some cases people are not going to be instantly on board and I know that can be frustrating for some people.”

Ryan, who will be chairman of the Republican National Convention in Cleveland this July, said that conservatives want to know if Trump shares their values, and added that simply saying the party is unified doesn’t make it so.

“At this point, I think that he needs to do more to unify this party and then to go forward and appeal to all Americans,” Ryan of Wisconsin told CNN.

Ryan’s refusal to follow Priebus’s lead in rallying behind Trump has no real precedent, but fits the mood of Republicans in Washington, many of whom fear the impact Trump’s nomination will have down the ballot.

Christie Outreach

Trump all but wrapped up the Republican nomination this week as his Tuesday victory in the Indiana primary led his only two remaining opponents, Ted Cruz and John Kasich, to drop out. On the Democratic side, Hillary Clinton has a large lead over Bernie Sanders, though he won in Indiana and is vowing to continue his campaign.

New Jersey Governor Chris Christie -- a Trump ally -- said Thursday that he plans to reach out to Ryan to discuss the speaker’s hesitation.

“Donald’s got work to do in bringing people together, but that’s not all that much different from other primaries,” Christie told reporters in Trenton.

But bridging the party’s gap between Trump’s brand of politics and Ryan’s won’t be easy.

Burden on Trump

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Ryan is a champion of free-trade deals Trump has blasted. Ryan has repeatedly tried behind the scenes to rally his party behind an immigration overhaul that would allow many illegal immigrants to stay in the U.S., while Trump has proposed a mass deportation force and the construction of a massive wall on the southern border. And Ryan recoils at the insults and outrageous rhetoric that fling regularly from Trump’s mouth.

Ryan, like Senate Majority Leader Mitch McConnell earlier this week, put the burden on Trump to bring party members together.

“Saying we’re unified doesn’t actually unify us,” said Ryan, who has been repeatedly critical of Trump’s comments and policies, including the candidate’s proposed temporary ban on Muslims entering the U.S.

“Conservatives want to know does he share our principles and values,” Ryan said.

McConnell Stance

“I have committed to supporting the nominee chosen by Republican voters, and Donald Trump, the presumptive nominee, is now on the verge of clinching that nomination,” McConnell of Kentucky said in a statement. “As the presumptive nominee, he now has the opportunity and the obligation to unite our party around our goals.”

Other establishment Republicans also made clear that they are unwilling to jump on the Trump train yet. The two living Republican presidents -- George W. Bush and George H.W. Bush -- are planning to skip the convention -- as are the most recent Republican nominees, Mitt Romney and Senator John McCain of Arizona.

Freshman Senator Ben Sasse of Nebraska is openly pushing for conservatives to rally around a third-party candidate, and others say they aren’t yet sold.

Mollifying Gestures

Trump, for his part, has made some gestures toward preparing for the fall campaign.

Trump shifted on one key point -- appointing Steven Mnuchin, a business associate of Trump’s and also chairman and CEO of Dune Capital Management LP, as finance chairman with a goal of raising $1 billion from donors.

And in what may have been an ill-fated attempt to appeal to Latinos, he tweeted out “I love Hispanics!” with a picture of him eating a fried taco salad.

Ryan was apparently surprised by the abrupt end to the primary campaign. A person close to the speaker said that he wasn’t prepared to make a decision about what to say about Trump because he thought he would have more time.

Ryan pointed out that House Republicans have their biggest House majority since 1928 and also control the Senate and most governorships.

“We have one more hill to climb, one more mountaintop,” Ryan said. “The stakes are extremely high.”

Latest Attacks

Ryan made clear he hasn’t been happy with Trump’s rhetoric to date, smiling through a recitation of Trump’s latest attacks on his fellow Republicans, including an attempt to link Ted Cruz’s father to the JFK assassination the morning of the Indiana primary.

“It’s time to set aside bullying and set aside belittlement,” Ryan said, and “appeal to what is good in us.”

Ryan expressed hope that Trump can pivot into that person and win the presidency in November.

“I think it is possible and we better get on with it,” Ryan said. “I think we can beat Hillary Clinton. Are you kidding me?”

Norm Ornstein, a congressional scholar with the American Enterprise Institute, said it was highly unusual, if not unprecedented, for a congressional leader of a major party not to support the party’s presumptive nominee.

“As best I can tell, this has not happened before,” Ornstein said in an e-mail. “Of course, the caveat -- maybe later -- may be a clever way to have it both ways, end up supporting your party’s nominee after indicating your misgivings. But even so, it is extraordinary.”